The e-commerce search glossary, no jargon

Index

The index is the "organized" version of your catalog that the search engine consults to answer a query — think of it as a book's table of contents rather than the book itself. Every time a product is added, changed, or removed from the catalog, the index needs to update to stay accurate.

Relevance

Relevance measures how well a result actually matches what the visitor was looking for. An engine can technically "work" (it returns results) while still being poorly relevant (the results aren't the ones expected). That's the difference between searching and finding.

Typo tolerance

This is the engine's ability to recognize a word despite one or more typing errors — an extra letter, a missing one, or a swap. Without this tolerance, "swetaer" and "sweater" are two completely different words to the engine, and the first will return nothing.

Synonyms

A synonym dictionary tailored to your catalog links different words your customers use for the same thing: "sweater" and "jumper," "sneakers" and "trainers." Without this setup, every vocabulary variation you didn't anticipate returns a blank page, even if the product exists.

Facets (faceted filters)

Facets are the filters shown alongside search results — size, color, price, brand. They let a visitor narrow down a result list without rephrasing their search. Well-built, they reflect how your customers actually think about their purchase, not your catalog's internal structure.

Ranking (sort order)

Ranking determines the order results are displayed in. By default, many engines sort purely by text match. A well-tuned ranking also factors in stock availability, margin, or popularity — business criteria, not just linguistic ones.

Zero-result query

This is a search that returns no results at all. Tracking this rate over time is one of the simplest and most telling indicators of a search engine's health: every zero-result query is a purchase intent that went nowhere.

Real-time indexing

This refers to how quickly a catalog change (new product, stock update, price change) is reflected in search results. Too much delay can make an out-of-stock product appear available, or vice versa.

None of these concepts are complex on their own. What makes the difference is knowing which ones are misconfigured on your specific site — and in what order to fix them.